(1) Field of the Invention
The present invention relates to the general technical field of safety systems for aircraft, and in particular for aircraft of the rotorcraft kind, e.g. helicopters.
The present invention relates more particularly to an emergency buoyancy system and to its method of control, and also to the associated aircraft. Such an emergency buoyancy system provides an aircraft with buoyancy and stability in the event of ditching in water, so as to allow the occupants to evacuate the aircraft. All aircraft that perform missions of transporting people over areas of sea are, in principle, fitted with such a buoyancy system.
(2) Description of Related Art
An emergency buoyancy system comprises floats that are deployed either under the control of the pilot and/or the copilot, or else that are triggered automatically, in particular by means of an immersion detector. Such floats may comprise bags that are inflated by explosive or electric deployment means, for example.
In present aircraft, an emergency buoyancy system is triggered manually in flight or in the event of the aircraft making contact with or impacting against water. The buoyancy system must previously have been engaged, by using a control button when overflying the sea while simultaneously having a speed of advance that is less than a speed known to be a maximum speed for proper deployment of the float. A pushbutton lights up once the buoyancy system is engaged to indicate that it is ready to operate. So long as the buoyancy system is not engaged, an erroneous operation on the control stick cannot trigger inflation of the floats.
Pressing on the lighted pushbutton or on a pushbutton on the control stick handle enables deployment of the floats to be triggered manually.
If the crew is unable to actuate the buoyancy system manually, deployment of the floats is triggered automatically by the immersion detector.
Document WO 2008/054401 discloses a system for inflating anticrash airbags, while taking account of the attitude of the aircraft and an excessive speed of descent.
Document U.S. Pat. No. 7,156,033 B2 discloses a buoyancy system associated with inhibitor means.
Document FR 1 383 688 discloses a helicopter having inflatable floats.
Document CA 2 481 789 suggests using an immersion sensor associated with an acceleration sensor in order to trigger the inflation of a float.
Known emergency buoyancy systems are advantageous. Nevertheless, untimely and undesired inflation of floats can occur in flight, e.g. because of very wet conditions. Untimely deployment of the floats takes the aircraft out of service in unwanted manner, at very least for the purpose of verifying the emergency buoyancy system.